A study of microstructure and hardness of bulk copper sample obtained by consolidating nanocrystalline powders using plasma pressure compaction

Bulk copper samples were prepared by consolidating ultrafine-grained copper powders using the technique of Plasma Pressure Compaction. The microstructure and hardness are compared with a sample made from consolidating micron-sized powders using identical processing conditions. Samples made by consolidating nanometer powders revealed evidence of grain coarsening and a higher density than the sample made from consolidating micron-sized powders. Both nanohardness and microhardness measurements revealed an increase in hardness of the bulk sample obtained by consolidating the smaller sized powders. Influence of powder particle size and processing variables on microstructure, to include the presence and distribution of artifacts, density, and microhardness are discussed.